<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>下拉菜单</title>
    <link rel="stylesheet" href="../css/bootstrap.min.css">
    <script src="../js/jquery-3.3.1.min.js"></script>
    <script src="../js/bootstrap.min.js"></script>
    <style>
        hr{
            margin: 0;
        }
    </style>
</head>
<body>
<div class="text-center">
    <div class="dropdown">
        <button class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
            按钮<span class="caret"></span>
        </button>
        <ul class="dropdown-menu">
            <li><a href="http://www.imooc.com">慕课网</a></li>
            <hr>
            <li><a href="http://www.baidu.com">百度</a></li>
            <hr>
            <li><a href="http://www.taobao.com">淘宝</a></li>
        </ul>
    </div>
</div>
</body>
</html>